📋 Case Study

Ethylene Oxide Absorption Column Design

Poor CO₂ co-absorption leading to catalyst poisoning and frequent shutdowns

🏗️ Project Overview

BASF ethylene oxide plant upgrade in Antwerp

🎯 Challenge

Poor CO₂ co-absorption leading to catalyst poisoning and frequent shutdowns

🔧 Design Approach

Switched from water to MDEA–water solvent; used SRK+EoS for accurate CO₂/H₂O/EO solubility and enthalpy of absorption

📐 Design Diagram

Ethylene Oxide Absorption ColumnMDEA–Water Solvent System | SRK+EoS ModelingEOCO₂φᵢ = CO₂:EO = 0.22Absorption Column(Packed, MDEA–H₂O)MDEA–H₂O(Low CO₂ affinity)Catalyst Poisoning(Due to residual CO₂)ΔHabs = −92 kJ/molSRK+EoS Model(CO₂/H₂O/EO solubility & enthalpy)

AI-generated project design illustration

📐 Key Calculations

Solubility Ratio (CO₂:EO)

φᵢ = yᵢP / xᵢγᵢPᵢˢᵃᵗ
Result: 0.22
Lower ratio = selective EO capture

Heat of Absorption

ΔH_abs = H_liq − (yᵢH_vap + xᵢH_liq)
Result: −92 kJ/mol
Drives reboiler duty & temperature profile

📊 Results

CO₂ removal increased from 63% to 94%, catalyst lifetime doubled, 19% lower steam consumption

💡 Lessons Learned

  • Activity coefficient models (NRTL) must be coupled with EOS for high-pressure non-ideality
  • Enthalpy departure functions are essential for energy balance accuracy

Key Takeaways

  • 1Activity coefficient models (NRTL) must be coupled with EOS for high-pressure non-ideality
  • 2Enthalpy departure functions are essential for energy balance accuracy